My dear Hooker.

I have been very idle not to have thanked you long ago for your very pleasant letter of June 24^th. which I could see you wrote to cheer me up, though at the time overburdened with correspondence. I liked your letter very much indeed, but do not write again, as it made me feel guilty.— Very many thanks about the Beards of the Russians.—² I cannot gain any strength & have given up the attempt to walk & have now got a pony lent me by Miss Lloyd (who is staying close by with Miss Cobbe) & this will perhaps do me some good & anyhow pass the time till I get home.—³

My object in writing to you now is to tell you that I have had a letter from D^r. Habel of N. York, who has staid 5 months at the Galapagos: I have told him,, if he collected plants, to communicate with you, & I hope I did rightly.⁴

From reading several essays by Nägeli & others I have come to think that it is all important with respect to the principles of Variability to learn all that we can about the polymorphic or protean genera, such as Rubus, Hieracium &c &c.⁵ Keep this, if you can, a little in your mind.

The New Zealand genera are interesting under this point of view. I want especially to hear of as many cases, as occur, of single species, or sections of genera, being tolerably fixed in form, whilst the other species are eminently variable.— From the time before writing the Origin, these genera have always seemed to me very perplexing.

We shall be at Down at very end of month.⁶

I am truly glad that you receive such comfortable accounts from N. Zealand about Willie.⁷

My dear old Friend | Yours affect | C. Darwin

PS. My note was written before receiving yesterday the paper on Snakes, which I have been very glad to read.⁸ I am strongly inclined to be a believer, not in fascination but in extreme fear which leads the wretched creature to fall into the snakes power, in same manner as many people feel inclined to throw themselves down a precipice. Similar accounts have been published about the Rattle-snake in U. States, which I have believed, though ridiculed. I go further & am much inclined to suspect, that the noises of the Rattle-snake & of the Puff adder, which are by no means dissimilar, serve to paralyse their prey with fear.—

I think the paper ought to be published,—if not in Linnean Journal, in Popular Science Jrnl or in the Annals or somewhere.⁹

Yours affect | C.D